Microhouse 2 - Soil Testing

There are two piles of soil to use, one is yellow and very clayey, the other is dark and more sandy and silty. the objective is to produce a stabilised earth brick

I'm quite sure that yellow pile is almost all clay and according to gernot minke's book, more than 30% clay for CEB's is no good. using cement for stabilising soil at the higher end of this clayey spectrum is not ideal either because it is incompatible with the clay - to much fine particle matter/glue with nothing to glue onto (but the different types of clay affect how true this statement is). you need to balance it out with more grainy sand to get a better matrix happenning. clay and cement are like the glue, the brick shouldn't be all glue but use the glue to bond ideally an event distribution of different sized particles. the higher clay content CEB's need other crazy ingredients instead of cement for stabilising like horse pee and ox blood, or lime.

If the intent is to get the most ideal concrete stabilised block at the maximum end of concrete in the mix @ 10%, then i would recomend from memory (will dive in deeper) that there be around 15% clay in the mix, using very sandy soil or sand to balance out the rest. Using less than 4% concrete in any ceb from stress tests appears to be a no no, so getting it right is pretty important here.

The dark soil pile being tested could be ideal. Although i don't know its history (how deep it was dug from the original top layer where it had its biology in there), if it was taken from underneath all the biological layer (usually about a foot deep and under is what you want). So far it looks like its going to come out at least 30% sandy 30% silt, perhaps more, but a good healthy distribution of the larger grains. depending on how much clay settles we can mix a small amount of that yellow pile in there to get a likely very good mix in terms of granularity and then add our cement. only thing about the dark soil is it may have a bit of biological content, I have no idea. it has no smell to me which is good. if there is biological content then it can create mold later, but i think for now this is going to be our best bet unless theres something I'm missing.

Thinking about this mixing of proportions now, we need to mark a meter out on the bucket when in its tilted position to gauge our volumes. We can fill it with water and add our markings every 50-100 liters of water added or so to do this, Marcin should I add this to the tasks? We need the tractor to do it and to weld the tabs on the mixer too.

I'm reading more about what our ideal proportions can be tonight. I shared the gernot mink book with everyone, the thing is deep but a must read anyone that wants to build with soil. the information in it can also be applied to rammed earth.